— Have a picnic this Saturday, OK?
— ________. I'm going to visit my parents in the countryside.
A:I can't agree more
B:I'm afraid not
C:I don't think so
D:Sounds great
— ____ you ____ to the park yesterday?
— Yes, I did. ( )
已知函数fx=-x2+2x,x≤0lnx+1,x>0,若|fx|≥ax,则a的取值范围是( )
下列光路图中,正确表示光从空气进入水中的是( )